Corrosion inhibition of copper and brass pigments in aqueous alkaline media by copolymers

Copper and brass pigments corrode in aqueous alkaline media with absorption of oxygen which can be measured gasvolumetrically. These corrosion reactions can be inhibited by certain copolymers, the metallic sparkle and the colour of the pigments being preserved. The brass pigment (rich gold) is inhibited more effectively by copolymers than the copper pigment. The corrosion inhibiting effect of styrene–maleic acid–acrylic ester copolymers on copper pigment decreases with increasing the chain length of the ester alcohol of the acrylate monomer. The most effective copolymer examined in this study is the styrene–maleic acid–ethyl acrylate copolymer which inhibited the corrosion reactions of copper and brass pigment both at pH 8.5 and 10.     

Viscosity index. I. Evaluation of selected copolymers incorporating n-octadecyl acrylate as viscosity index improvers

Compositionally and structurally varied copolymers all containing n-octadecyl acrylate were prepared and evaluated as viscosity index improvers in a common base oil under conditions of low shear. Systems evaluated over a range of copolymer and blend composition were: copolymers of n-octadecyl acrylate with, respectively, methyl methacrylate, 2-ethylhexyl acrylate, and n-dodecyl acrylate; and homopolymers of poly(n-octadecyl acrylate), prepared with a wide range of molecular weights. Properties were compared with those of blends of commercial methacrylate copolymers (acryloids) which had been freed of their entraining liquid. Mixtures of base oil with copolymers of n-octadecyl acrylate and methyl methacrylate, compared at fixed SAE viscosities, were the most efficient of all blends studied. They had the smallest rate of change of viscosity with temperature (as measured by their ASTM slopes), particularly in the composition region of incipient polymer precipitation at room temperature. Efficiency of certain of these composition was somewhat greater than that of the acryloids. A parameter that related concentration and weight-average molecular weight was used to correlate all of the data for ASTM slope and viscosity. Empirical relations developed by using this parameter enabled rheological data to be estimated that agree within 6% of experimental values for the case of thermodynamically good base oil solvents. These data demonstrated the relatively small contributions of copolymer structure to viscosity index improvement.     

Terpolymers. I. The mechanical properties and transition temperatures of terpolymers of n-octadecyl acrylate,ethyl acrylate,and acrylonitrile

Earlier work revealed that the internal plasticization of polyacrylonitrile by the higher n-alkyl acrylates or N-n-alkylacrylamides yielded only brittle copolymers. This difficulty was circumvented in the present work by starting with copolymers of acrylonitrile and ethyl acrylate, over the range of compositions, and further modifying these by incrementally displacing the ethyl acrylate in each recipe by n-octadecyl acrylate through terpolymerization. In this way, the stepwise small reduction in T_g for the base ethyl acrylate–acrylonitrile copolymers was greatly increased for each of the terpolymers. Compositions were obtained ranging from glassy, brittle terpolymers, with glass transitions above room temperature, to soft plasticized polymers having sufficient polar networks retained from the nitrile to confer useful properties. The decline in the glass temperature was shown to be dependent on the free volume conferred by the side-chain methylene groups of each acrylate ester. In contrast, the decline in tensile and flexural strengths and moduli for the terpolymers having glass transitions above room temperature was produced entirely by the presence of the methylene groups of the 18-carbon ester. The glass transition region corresponded to room temperature when the acrylonitrile content of the base copolymer had been reduced to 50 mole-%. Terpolymers of this nitrile content and lower had the low moduli and large elongations of plasticized compositions. An equation was developed which correlated empirically the glass transitions and the mechanical properties with the weight fraction of the acrylate esters for the glassy terpolymers.     

Styrene copolymers with carboxyl groups as corrosion inhibitors for zinc pigments in aqueous alkaline media

Zinc pigments react in aqueous alkaline media (e.g., water-borne paints) by the evolution of hydrogen. Low molecular weight styrene-maleic acid and styrene-acrylic acid/styrene-acrylate copolymers can inhibit this corrosion reaction of zinc pigments in a mixture of water and butyl glycol in the ratio 9 : 1 at a pH value of 10 (ammonia). High molecular weight styrene-maleic acid copolymers are only very poor corrosion inhibitors. This was proved by volumetric measurement of the evolved hydrogen. There seems to be a correlation between the content of carboxyl groups of the low molecular weight styrene-maleic acid and styrene-acrylic acid/styrene-acrylate copolymers and the evolved hydrogen volume in ammoniacal aqueous medium: The lower the acid number of the styrene copolymers, the lower is the evolved hydrogen volume. Low molecular weight styrene copolymers neutralized with dimethylethanolamine inhibit the corrosion reaction much better than with ammonia. © 1996 John Wiley & Sons, Inc.     

Synthesis of copolymers of N,N-dimethyl acrylamide and methacrylate esters and their surface tensions

A systematic study was made on the preparation of N,N-dimethylacrylamide (NDMA)/ methacrylic ester statistical copolymers. The methacrylic ester comonomers used in the copolymerizations were ethyl, n-butyl, n-hexyl, n-octyl, n-dodecyl, n-hexadecyl, and n-octadecyl methacrylates. It was found that the NDMA copolymers could be prepared in three molecular weight regions: 1.0 × 10⁴, 2.0 × 10⁵, and greater than 1.0 × 10⁶ ([η] in water at 30°C of 0.1, 0.6, and greater than 1.5 dL/g, respectively). The molecular weights of the copolymers were dependent on the solvent employed in the polymerizations and on the presence of a chain transfer agent (t-dodecyl mercaptan). All copolymer compositional analyses were made by 400 MHz ¹H-NMR spectroscopy. The NDMA/methacrylic ester copolymers decreased the surface tension of water in the order: C₄ = C₆ > C₈ > C₁₂ > C₁₆ > C₂ = C₁₈ > P(NDMA), lowest surface tension (35 dyn/cm) to highest surface tension (59 dyn/cm).     

Acrylate–vinylidene chloride copolymers derived from corresponding water‐borne latexes: Influence of acrylate units on their potential as heavy‐duty anticorrosive coating materials

A series of aqueous latexes with solid contents of 56%–59% were synthesized by binary emulsion copolymerization of vinylidene chloride (VDC) with an acrylate, namely methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), hexyl acrylate (HA), or 2‐ethylhexyl acrylate (EHA). Differential scanning calorimetry (DSC) and Fourier‐transform infrared (FTIR) spectroscopy showed that the acrylate units with short ester side‐chains, such as MA and EA, made the copolymers hard and the crystallization tendency of their PVDC segments was reduced. Hydrophobic acrylates with relatively long ester groups, such as HA and EHA, gave flexible copolymers, and favored the crystallization of their PVDC segments. BA endowed the copolymers with medium flexibility and crystallization tendency. As coating materials, the copolymers bearing MA and EA adhered poorly to the tinplate before or after 100 hr of salt‐spray corrosion, whereas those bearing BA, HA, or EHA showed good adhesion to tinplate when they had little or no crystallinity. After 100 hr of salt‐spray corrosion, only BA–VDC80, containing 80% VDC, retained both excellent adhesion to metal and excellent barrier performance. Further study demonstrated that BA–VDC80 could protect tinplate from rusting for at least 250 hr under harsh salt‐spray corrosion. Scanning electron microscopy, FTIR‐attenuated total reflectance spectroscopy and DSC were used to evaluate the corroded BA–VDC80 film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40192.     

Mechanical properties and transition temperatures of copolymers of N-n-alkylacrylamides and vinylidene chloride

Mechanical and solution properties, melting transitions, torsional stiffness temperatures, T_f, and selected modulus-temperature curves are presented for copolymers of the N-n-alkylacrylamides with vinylidene chloride. Copolymers were prepared at 60°C across the range of compositions, using as comonomers N-n-butyl-, octyl-, dodecyl- and oleyl-acrylamide, which have amorphous side-chains, and N-n-octadecyl acrylamide and n-octadecyl acrylate whose side-chains are crystalline. The mechanical properties reflected the effect of the decline in backbone crystallinity and the simultaneous development of strong intermolecular interactions in the amorphous stage. Copolymers were stiff or showed brittle failure across the compositional range except when intermolecular forces were reduced (with n-octadrcyl acrylate) and side-chain crystallization eliminated (with N-oleylacrylamide). These systems and the n-dodecylacrylamide copolymers had yield strengths less than brittle strengths and substantial elongations. Backbone crystallinity was eliminated at about 15 mole % amide and side-chain crystallinity vanished at less than 10 mole % of the amide in the N-n-octadecylacrylamide series. No depression in side-chain melting point occurred with dilution by segments of vinylidene chloride. Over-all decline in the flex-temperature was the normal monotonic function of composition except that values increased in magnitude at high vinylidene chloride contents, the effect presumably being caused by the presence of crystallinity. An empirical equation was developed which permitted the calculation of T_f for any N-n-alkylacrylamide composition with any number of carbon atoms in the side-chain, above 3.     

Synthesis of copolymers of N,N-dimethyl acrylamide and methacrylate esters and their surface tensions

A systematic study of the preparation of N,N-dimethylacrylamide (NDMA)/methacrylic ester statistical copolymers was conducted. The methacrylic ester comonomers used in the copolymerizations were ethyl, n-butyl, n-hexyl, n-octyl, n-dodecyl, n-hexadecyl, and n-octadecyl methacrylates. It was found that the NDMA copolymers could be prepared in three molecular weight regions 1.0 × 10⁴, 2.0 × 10⁵, and greater than 1.0 × 10⁶ ([η] in water at 30°C of 0.1, 0.6, and greater than 1.5 dL/g, respectively). The molecular weights of the copolymers were dependent on the solvent employed in the polymerizations and on the presence of chain transfer agent (t-dodecyl mercaptan). All copolymer compositional analyses were made by 400 MH_z ¹H-NMR spectroscopy. The NDMA/methacrylic ester copolymers decreased the surface tension of water in the order: C₄ = C₆ > C₈ > C₁₂ > C₁₆ > C₂ = C₁₈ > P(NDMA), from lowest surface tension (35 dyn/cm) to highest surface tension (59 dyn/cm).     

Viscosity index. III. Thermodynamic parameters for side chain crystallinity in pour point-modified blends containing n-octadecyl acrylate

The melting transitions and heats of fusion were obtained by differential scanning calorimetry for the crystalline phase of the same mixtures whose rheological properties were reported in the previous two papers. Pour point temperatures were also determined. In addition, the same thermodynamic quantities were also collected for higher polymer concentrations in this work, thus encompassing the entire concentration range. The DSC scans revealed that the distribution of crystallite sizes characteristic of the bulk copolymers was retained in the blends. Phase diagrams indicated isomorphism in all systems studied. An equation was derived to predict the influence of diluent concentration on melting point depression of copolymers, in which one component crystallizes through its side chains but in which the side chains of the other remain amorphous. The difference between the experimental heats of fusion and the value for entirely crystalline poly(n-octadecyl acrylate) were used to estimate extent of apparent cocrystallization of the different copolymers with the base oil. While this tended to increase with pour point-depressant ability, concomitant crystallinity of wax and depressant were essential to successful wax crystal modification. A mechanism is proposed in which whole molecules of hexagonally packed copolymers are attached to wax nuclei and accumulate slowly a t low diffusion rates. Thus, growth occurs over small crystal areas and is considered responsible for the directing influence of copolymer depressant. The resulting small crystal sizes, accompanied by fast growth of rapidly diffusing paraffins on uncontaminated surfaces, promote more compact habits, like dendrites that postpone network formation to lower temperatures. It was concluded that a melting point difference of less than 25°C between bulk copolymer and base oil is required for successful pour point depression. Consequently, in this base oil, only copolymers with long amorphous side chains in a limited composition range, such as the n-octadecyl acrylate–2-ethylhexyl acrylate copolymers, possessed sufficient lattice disorder to meet the specification. The rest produced gelation at higher temperatures.     

Thermal and sonochemical degradation kinetics of poly(n‐butyl methacrylate‐co‐alkyl acrylates): Variation of chain strength and stability with copolymer composition

The thermal degradation of poly(n‐butyl methacrylate‐co‐alkyl acrylate) was compared with ultrasonic degradation. For this purpose, different compositions of poly (n‐butyl methacrylate‐co‐methyl acrylate) (PBMAMA) and a particular composition of poly(n‐butyl methacrylate‐co‐ethyl acrylate) (PBMAEA) and poly(n‐butyl methacrylate‐co‐butyl acrylate) (PBMABA) were synthesized and characterized. The thermal degradation of polymers shows that the poly(alkyl acrylates) degrade in a single stage by random chain scission and poly(n‐butyl methacrylate) degrades in two stages. The number of stages of thermal degradation of copolymers was same as the majority component of the copolymer. The activation energy corresponding to random chain scission increased and then decreased with an increase of n‐butyl methacrylate fraction in copolymer. The effect of methyl acrylate content, alkyl acrylate substituent, and solvents on the ultrasonic degradation of these copolymers was investigated. A continuous distribution kinetics model was used to determine the degradation rate coefficients. The degradation rate coefficient of PBMAMA varied nonlinearly with n‐butyl methacrylate content. The degradation of poly (n‐butyl methacrylate‐co‐alkyl acrylate) followed the order: PBMAMA < PBMAEA < PBMABA. The variation in the degradation rate constant with composition of the copolymer was discussed in relation to the competing effects of the stretching of the polymer in solution and the electron displacement in the main chain. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Melt viscosity characteristics of methacrylate–styrene copolymers

The activation energies of flow E_A of methacrylate–styrene copolymers containing n-butyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-tridecyl, n-octadecyl, and cyclohexyl methacrylate have been investigated as a function of molecular weight, composition, and methacrylate monomer. Below a critical pendent group molar volume per chain unit (120 ± 10 ml Le Bas units), E_A was found to increase with molar volume; and above this value, a decrease in E_A was observed, reflecting a decrease in copolymer density. Copolymers with pendent group molar volumes per average chain unit of between 96 and 140 ml (Le Bas units) were found to exhibit sufficiently high E_A values to render them suitable for use in thermoplastic and photothermoplastic devices with superior development and erasure rates, at temperatures which enabled the attainment of the development and erasure viscosities with a low expenditure of heat energy. Methacrylate–styrene copolymers with long-chain ester methacrylates (viz., n-decyl and n-dodecyl methacrylate) were found to exhibit critical molecular weights M_c below 3000; and M_c was found to decrease with increasing methacrylate tail length and methacrylate concentration. These M_c values correspond to critical chain lengths Z_c below 45. Similar Z_c values have been previously reported for acrylonitrile–methyl methacrylate copolymers³⁰ and ethylene–propylene copolymers.²⁸     

Polymeric corrosion inhibitors for aluminium pigment

In aqueous alkaline media (e.g. water-borne metallic paints) aluminium pigments react by the evolution of hydrogen. This corrosion reaction can be inhibited by addition of different water-soluble polymers with carboxyl groups like polyacrylic acids, styrene–maleic acid or styrene–acrylate copolymers. As a rough empirical rule can be stated that the corrosion-inhibiting effect of polymers with carboxyl groups increases with decreasing molecular mass and decreasing acid number. Moreover, the isoelectric point (IEP) of aluminium oxide (pH≈9) seems to be an important factor controlling corrosion inhibition (and adsorption) of polymers with carboxyl groups. Thermosetting phenolic resins (resoles) inhibit the corrosion reaction of aluminium pigment excellently at pH 8 but less effectively at pH 10. The corrosion-inhibiting functional group of resoles seems to be the chelating ortho-hydroxybenzyl alcohol structural part. In contrast, the nonionic water-soluble polymer polyvinyl alcohol does not inhibit the corrosion reaction. So, one may assume that an ionic interaction between aluminium pigment surface and polymer is necessary (but not sufficient) for corrosion inhibition.     

Stabilization of aluminum pigment in waterborne paints

The corrosion of aluminum pigments in aqueous alkaline paint media, which results in the evolution of hydrgen, can be inhibited by certain substances. The combination of noninhibiting paint resins with three corrosion inhibitors (salicylic acid, a fluorinated phosphate surfactant, and an epoxy ester resin) has been studied. The presence of the resins does not significantly affect the stabilization of the aluminum pigment at pH 10 by the corrosion inhibitors. With the addition of corrosion inhibitors, the hydrogen volume evolved from aqueous aluminum pigment dispersions is surprisingly reduced by stirring. However, when heated to +40°C aqueous aluminum pigment dispersions with inhibitors evolve more hydrogen; at pH 8 the results are still satisfactory even at +40°C.     

Emulsifier‐free reversible addition–fragmentation chain transfer emulsion polymerization of alkyl acrylates mediated by symmetrical trithiocarbonates based on poly(acrylic acid)

Emulsifier‐free batch emulsion polymerization of n‐butyl acrylate and its semi‐batch copolymerization with 2,2,3,3,4,4,5,5‐octafluoropentyl acrylate and 2,2,3,4,4,4‐hexafluorobutyl acrylate both mediated by poly(acrylic acid) containing the trithiocarbonate group in the chain was employed to produce amphiphilic triblock copolymers. The polymerization‐induced self‐assembly of these copolymers in aqueous media gave rise to spherical core–shell particles. Irrespective of the experimental conditions, the polymeric product was characterized by a bimodal molecular weight distribution. The apparent violation of the reversible addition–fragmentation chain transfer polymerization mechanism may be attributed to restricted accessibility of the trithiocarbonate group in the self‐assembled block copolymers for propagating radicals that enter into the particle. Mean‐field theoretical arguments were employed to explain the exclusively spherical morphology of the particles observed in the experiment. © 2019 Society of Chemical Industry     

Experimental investigation on high conversion free-radical polymerization of behenyl acrylate

An experimental investigation on the kinetics of free-radical polymerization of behenyl (a mixture of 14.8% n-octadecyl, 15.1% n-docosyl) acrylate initiated with benzoyl peroxide was conducted at 70°C using a HAAKE rotational viscometer. Molecular weight measurements and differential scanning calorimetric studies of the samples are also described and the results are compared with those obtained by batch reactions conducted under a nitrogen atmosphere. A high monomer order of 1.61±0.11 and a low initiator order of 0.35±0.04 was obtained. The role played by the long methylene chain in behenyl acrylate is also discussed. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of temperature‐responsive poly(vinyl alcohol)‐based copolymers

A poly(vinyl alcohol) (PVA)/sodium acrylate (AANa) copolymer was synthesized to improve the water solubility of PVA at the ambient temperature. Furthermore, a series of temperature‐responsive acetalyzed poly(vinyl alcohol) (APVA)‐co‐AANa samples of various chain lengths, degrees of acetalysis (DAs), and comonomer contents were prepared via an acid‐catalysis process. Fourier transform infrared and ¹H‐NMR techniques were used to analyze the compositions of the copolymers. The measurement of the turbidity change for APVA‐co‐AANa aqueous solutions at different temperatures revealed that the lower critical solution temperature (LCST) of the copolymers could be tailored through the control of the molecular weight of the starting PVA‐co‐AANa, DA, and comonomer ratios. Lower LCSTs were observed for APVA‐co‐AANa with a longer chain length, a higher DA, and fewer acrylic acid segments. In addition, the LCSTs of the APVA‐co‐AANa aqueous solutions appeared to be salt‐sensitive. The LCSTs decreased as the concentration of NaCl increased. Moreover, atomic force microscopy images of APVA‐co‐AANa around the LCST also proved the temperature sensitivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study on modified phenolic resin. III. Modification with p-hydroxyphenylmaleimide/acrylic ester copolymer

The improvement of toughness and heat resistance of phenolic resin was examined by blend of novolac and copolymers prepared from p-hydroxyphenylmaleimide (HPMI) and acrylic ester. Copolymers of HPMI and acrylic esters, such as methyl acrylate, ethylacrylate, n-butylacrylate, or 2-ethylhexyl acrylate, were synthesized. Average molecular weights, glass transition temperatures (T_g) and thermal decomposition temperatures were measured. The miscibility of the copolymers with novolac was evaluated. It was found that these copolymers had higher average molecular weight and higher thermal decomposition temperature than those of novolac; they also had good miscibility with novolac. Molding compounds were prepared by hot roll-kneading of mixtures, which involved novolac, the copolymer, hexamethylenetetramine (hexamine), and glass fiber. Test pieces of the modified phenolic resins were prepared by transfer molding from the molding compounds. It was found that phenolic resin, modified with HPMI/ethylacrylate copolymer or HPMI/n-butylacrylate copolymer, which consisted of numerous units of acrylic ester, showed both good toughness and good heat resistance.     

Degradable micelles based on hydrolytically degradable amphiphilic graft copolymers for doxorubicin delivery

Micelles based on a low-toxic and hydrolytically degradable poly(β-amino ester)-g-octadecyl acrylate (PAE-g-ODA) amphiphilic copolymer were developed for doxorubicin (DOX) delivery. A two-step reaction pathway was used to synthesize PAE-g-ODA copolymers with poly(ethylene glycol) segments in the backbone via Michael-type addition reaction. Copolymers with various grafting degrees were obtained by tuning the feeding molar ratios of acrylate/formed secondary amine and the grafting reaction time. Among this series of copolymers, PAE-g-ODA-2 (PAE-g-ODA with 45% ODA side chains) were found to form spherical micelles with an average size of 72.5 nm, as determined by dynamic light scattering (DLS) and transmission electron microscope (TEM), whereas the other PAE-g-ODA copolymers fail to form stable micelles with a narrow size distribution in an aqueous solution. The titration curve illustrated that PAE-g-ODA-2 has a high buffer capacity in the pH range of 7.5-5. The hydrolytic degradation of PAE-g-ODA-2 copolymer in PBS buffer (pH 7.4, 37 °C) was monitored by ¹H NMR. It was found that up to 70% ester groups in the backbones were hydrolyzed in 48 h. The DOX-loaded micelles release about 70% trapped DOX within 48 h in physiological condition. Cytotoxicity assay showed a low cytotoxicity of PAE-g-ODA-2 micelles as well as a higher inhibition against HepG2 tumor cells of DOX-loaded micelles than free DOX.     

Properties of n‐butyl methacrylate copolymer latex films derived from crosslinked latex particles

Films obtained from copolymer latexes of n‐butyl methacrylate (BMA) with a series of crosslinking monomers [i.e., a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), and aliphatic urethane acrylate] exhibited differences in their tensile properties and swelling behaviors. For P(BMA‐co‐EGDMA) copolymer, a dependence on the initiator type was obtained. It is postulated that the network microstructures for the various copolymers evolved as the result of the copolymerization reactions between the monomer pairs during the synthesis in the miniemulsion free‐radical copolymerization. These network microstructures are, therefore, hypothesized to influence the mechanical properties of the resultant films. Copolymers prepared with Mac were tough in comparison with copolymers made with EGDMA. The presence of longer linear or lightly crosslinked poly(n‐butyl methacrylate) (PBMA) chains and the looseness of the crosslinked network structures in the PBMA‐co‐Mac copolymers appear to be the factors responsible for the differences. All of the copolymer films disintegrated into swollen individual microgels when they were immersed in tetrahydrofuran. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 42–49, 2003     

Separation of organic solvent from dilute aqueous solutions and from organic solvent mixtures through crosslinked acrylate copolymer membranes by pervaporation

The composite membranes of acrylate polymers and porous substrate were prepared. The separation of the organic solvent–water mixtures and the organic solvent–organic solvent mixtures through these membranes by pervaporation was investigated. The acrylate copolymer membrane showed the organic solvent permselectivity for the separation of the organic solvent–water mixture, especially for the chlorinated hydrocarbon–water mixture separation. The high organic solvent permselectivity should be governed by solubility selectivity. The influence of the ester residue of acrylate on the phenol–water mixture separation was observed. The copolymerization of the macromonomers containing the polystyrene, poly(methyl methacrylate), and polydimethylsiloxane chain had a small effect on the separation of the chlorinated hydrocarbon–water mixture. High flux and low selectivity of organic solvent were observed in the case of the organic solvent mixture separation through the n-butylacrylate membrane. The difference of permeability of organic solvent was observed for the acrylate copolymer which has various structures of ester residue. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 1483–1494, 1998